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	<title>ASCII folding token filter | ElasticSearch 7.7 权威指南中文版</title>
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                            <div style="color:gray; word-break: break-all; font-size:12px;">原英文版地址: <a href="https://www.elastic.co/guide/en/elasticsearch/reference/7.7/analysis-asciifolding-tokenfilter.html" rel="nofollow" target="_blank">https://www.elastic.co/guide/en/elasticsearch/reference/7.7/analysis-asciifolding-tokenfilter.html</a>, 原文档版权归 www.elastic.co 所有<br/>本地英文版地址: <a href="../en/analysis-asciifolding-tokenfilter.html" rel="nofollow" target="_blank">../en/analysis-asciifolding-tokenfilter.html</a></div>
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<strong>重要</strong>: 此版本不会发布额外的bug修复或文档更新。最新信息请参考 <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/index.html" rel="nofollow">当前版本文档</a>。
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<h2 class="title">
<a id="analysis-asciifolding-tokenfilter"></a>ASCII folding token filter<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/analysis/tokenfilters/asciifolding-tokenfilter.asciidoc">edit</a>
</h2>
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<p>Converts alphabetic, numeric, and symbolic characters that are not in the Basic
Latin Unicode block (first 127 ASCII characters) to their ASCII equivalent, if
one exists. For example, the filter changes <code class="literal">à</code> to <code class="literal">a</code>.</p>
<p>This filter uses Lucene’s
<a href="https://lucene.apache.org/core/8_5_1/analyzers-common/org/apache/lucene/analysis/miscellaneous/ASCIIFoldingFilter.html" class="ulink" target="_top">ASCIIFoldingFilter</a>.</p>
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<div class="titlepage"><div><div>
<h3 class="title">
<a id="analysis-asciifolding-tokenfilter-analyze-ex"></a>Example<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/analysis/tokenfilters/asciifolding-tokenfilter.asciidoc">edit</a>
</h3>
</div></div></div>
<p>The following <a class="xref" href="indices-analyze.html" title="Analyze API">analyze API</a> request uses the <code class="literal">asciifolding</code>
filter to drop the diacritical marks in <code class="literal">açaí à la carte</code>:</p>
<div class="pre_wrapper lang-console">
<pre class="programlisting prettyprint lang-console">GET /_analyze
{
  "tokenizer" : "standard",
  "filter" : ["asciifolding"],
  "text" : "açaí à la carte"
}</pre>
</div>
<div class="console_widget" data-snippet="snippets/894.console"></div>
<p>The filter produces the following tokens:</p>
<div class="pre_wrapper lang-text">
<pre class="programlisting prettyprint lang-text">[ acai, a, la, carte ]</pre>
</div>
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<h3 class="title">
<a id="analysis-asciifolding-tokenfilter-analyzer-ex"></a>Add to an analyzer<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/analysis/tokenfilters/asciifolding-tokenfilter.asciidoc">edit</a>
</h3>
</div></div></div>
<p>The following <a class="xref" href="indices-create-index.html" title="Create index API">create index API</a> request uses the
<code class="literal">asciifolding</code> filter to configure a new
<a class="xref" href="analysis-custom-analyzer.html" title="Create a custom analyzer">custom analyzer</a>.</p>
<div class="pre_wrapper lang-console">
<pre class="programlisting prettyprint lang-console">PUT /asciifold_example
{
    "settings" : {
        "analysis" : {
            "analyzer" : {
                "standard_asciifolding" : {
                    "tokenizer" : "standard",
                    "filter" : ["asciifolding"]
                }
            }
        }
    }
}</pre>
</div>
<div class="console_widget" data-snippet="snippets/895.console"></div>
</div>

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<div class="titlepage"><div><div>
<h3 class="title">
<a id="analysis-asciifolding-tokenfilter-configure-parms"></a>Configurable parameters<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/analysis/tokenfilters/asciifolding-tokenfilter.asciidoc">edit</a>
</h3>
</div></div></div>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<code class="literal">preserve_original</code>
</span>
</dt>
<dd>
(Optional, boolean)
If <code class="literal">true</code>, emit both original tokens and folded tokens.
Defaults to <code class="literal">false</code>.
</dd>
</dl>
</div>
</div>

<div class="section">
<div class="titlepage"><div><div>
<h3 class="title">
<a id="analysis-asciifolding-tokenfilter-customize"></a>Customize<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/analysis/tokenfilters/asciifolding-tokenfilter.asciidoc">edit</a>
</h3>
</div></div></div>
<p>To customize the <code class="literal">asciifolding</code> filter, duplicate it to create the basis
for a new custom token filter. You can modify the filter using its configurable
parameters.</p>
<p>For example, the following request creates a custom <code class="literal">asciifolding</code> filter with
<code class="literal">preserve_original</code> set to true:</p>
<div class="pre_wrapper lang-console">
<pre class="programlisting prettyprint lang-console">PUT /asciifold_example
{
    "settings" : {
        "analysis" : {
            "analyzer" : {
                "standard_asciifolding" : {
                    "tokenizer" : "standard",
                    "filter" : ["my_ascii_folding"]
                }
            },
            "filter" : {
                "my_ascii_folding" : {
                    "type" : "asciifolding",
                    "preserve_original" : true
                }
            }
        }
    }
}</pre>
</div>
<div class="console_widget" data-snippet="snippets/896.console"></div>
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